OLED (Organic Light-Emitting Diode) display screens have been listed as the next-generation display technique with much prospect for development due to their advantages such as thinness, light weight, wide perspective, active luminescence, continuous and tunable emission colors, low cost, rapid responding speed, low energy consumption, low driving voltage, wide range for operating temperature, simple fabrication process, high emission efficiency, and flexibility display, etc.
An OLED basic structure includes an anode, a cathode and an organic light emitting layer located between the anode and the cathode. OLED luminescence refers to a phenomenon of light emission caused by the anode and cathode carriers pouring-in and recombining, as the organic light emitting layer is driven by an applied electric field. Specifically, electrons and holes as the carriers are shifted from the cathode and the anode respectively to the organic light emitting layer under the effect of the electric field and meet in the organic light emitting layer for recombination to form excitons, which excitons are deactivated to release energy, and the released energy is to excite the light emitting molecules in the organic light emitting layer and the excited light emitting molecules to undergo radiative relaxation and thereby emit visible light.
OLEDs may be divided into the two types of Passive Matrix OLEDs (PMOLED) and Active Matrix OLEDs (AMOLED) depending on different driving modes, of which the PMOLED consists of cathodes and anodes in matrix form, scan-illuminating pixels in the arrays, where each pixel is operated in a short-pulse mode and emits light instantaneously in high luminance, and with a simple structure thereof, it can effectively reduce the manufacturing cost, but is not suited for application in large-sized and high-resolution display panels for its driving voltage is comparatively high. The AMOLED instead uses an independent Thin Film Transistor (TFT) to control each pixel, where each pixel can be continuously and independently driven to emit light, and since the AMOLED requires a lower driving voltage and has a longer life, it is applicable to large-sized tablet display, whereas its manufacturing process is more complicated and higher in cost.
In the prior art, an AMOLED display panel comprises a plurality of pixel units arranged in arrays. As shown in FIG. 1, each pixel unit 100 includes a red light emitting device 2, a green light emitting device 3 and a blue light emitting device 4 disposed in parallel, and a thin film transistor 5 corresponding to each color light emitting device.
Current AMOLED display panels have the drawback that when the screen is viewed from a close distance, the pixel units are presented with color edge phenomenon, thus affecting the display effect of the display panel. In addition, the light emitting layers for each color light emitting device need to be formed using independent precision metal mask evaporation, which results in a comparatively high manufacturing cost for such display panels.